AstrophysicistMario Livio worked on the Hubble Space Telescope for almost 25 years, until 2015. Throughout his scientific career, he has not only written hundreds of scientific articles and books on subjects ranging from theGolden Ratio to brilliant scientists’big blunders—he’s also extended his creative reach to musical collaborations, including in his role as Science Advisor to the Baltimore Symphony Orchestra.

Livio’s latest book, Why?: What Makes Us Curious, is, by his own admission, the farthest afield from his usual subjects of study. But it’s no surprise that someone with as wide a scope of interests as Livio would want to know more about the nature of curiosity itself. We spoke by phone one Thursday morning in early June about what we know thus far about how curiosity works, the purpose it serves, and how to nurture curiosity in children. Livio also answered, with the patience and enthusiasm of an excellent teacher, my rudimentary questions about telescopes and astrophysics, and calmed the terror I feel when I think about how our universe is expanding into nothingness.

I thought we could start with you defining what curiosity is and the way you came to understand it through researching this book.

It’s funny that you should ask this question because one of the things that I concluded in the book, and this was only after I did all the research and everything, is that when we talk about curiosity, it turns out that there are several mechanisms involved. There is a curiosity that we feel when we see something that surprises us or when there is something ambiguous and we want to understand that. But it’s a relatively transitory-type feeling. There is a curiosity that we feel when we cannot remember the name of the actor who played in this or that film. That is another type of curiosity. And then there is the curiosity that drives, for example, all basic scientific research, and that’s our love for knowledge.

So while you will see various types of definitions, like a state for acquiring information and things like that, those never quite capture everything that is involved. Had we known as much we know now about curiosity, we might have invented different words for these different mechanisms.

As a highly curious person, of course you’d be curious about the nature of curiosity itself. But what was the very first thread of the book or the research for you?

As you noted correctly, I have always been a very curious person and I have always been curious about many things. I have various colleagues who are excellent scientists but interested in relatively few things outside of that. I have always loved art, and I was always interested in music, as well as in my scientific research.

When did I first think of doing a book about this? I think that type of thought has been in my mind for a long time, but I did not think that I could do a book about it because I wasn’t fully aware of all the research that has been done, and curiosity itself is not an area of expertise for me. Before this, I tended to write about things that were closer to what I actually do, even if they weren’t precisely the things that I do.

When I began looking into curiosity, I was amazed to discover that not that much has been done yet. In spite of the importance of curiosity, there aren’t that many people who specifically work on this topic. So I think that was when I started realizing that maybe I could write a book about it.

Why do you think it is that not many people specifically study this topic?

I think partly probably because it’s hard. You know? There are lots of people who talk about consciousness, but very few will dare to define it very precisely. And while people are investigating various aspects of consciousness, you will not find very many people who say, “My research is on human consciousness.” There is a similar thing about curiosity.

You refer often in the book to Daniel Berlyne’s formulation of the different types of curiosity. Can you walk me through it?

Yes. It is a way to help map curiosity onto a two-dimensional plane. And while that mapping is definitely not unique—you could perhaps invent other types of mappings—I found it to be very fruitful in the sense that it helps you discuss some of these different mechanisms of curiosity.

One axis goes from perceptual to epistemic curiosity. Perceptual curiosity is that curiosity that we feel when we see something new, something surprising or something very puzzling or ambiguous. I give the example of Asian children in some remote village who see a white person for the first time—that is perceptual curiosity. Epistemic curiosity, which is at the other end of that axis, is the love for knowledge. That is really what is driving all scientific research, it’s driving those explorations which can sometimes last a lifetime.

And then on the other axis are diversive and specific curiosity. Specific curiosity is when you are curious about a very specific piece of information, a small missing piece in the puzzle. So that would be, “What was the name of that book I read three days ago?” This type of curiosity can be relatively easily satisfied if you provide that one piece of information. Diversive curiosity is what you do to ward off boredom. So when you see young people continuously text messaging or checking for text messages or browsing the internet without any specific goal in mind, that’s diversive curiosity.

You interviewed a lot of people who you consider to be exceptionally curious for this book. What in other people alerts you to the fact that they may be exceptionally curious, and then what criteria did you use for selecting the people with whom you wanted to speak?

It is hard. Nobody can really measure how curious a person is. And also, it’s very hard to tell somebody, “Be curious now.” You know? This is actually what affects some of the functional MRI experiments, because you want to look at people’s brains when they are being curious, but you cannot order them to be curious. So the way I selected people was: I more or less looked for people who are at some level polymaths, interested in many fields. I took that to be some sort of a surrogate for curiosity, because how could somebody not be curious if they have been involved in all these different things and show such openness to trying to solve problems in different disciplines? So that was my main criterion for choosing them.

If you are talking to somebody at a party and you get the sense that they are not a very curious person, do you have an adverse reaction to that? Basically, would you enjoy talking with somebody who is not curious?

Of course there are people who are more curious than others, but my claim is that most people are curious about something. I mean some people are curious about science and things like that and so on, and others may be curious about gossip, and yet others may be curious about what’s happening in Congress. But most people have a curiosity about something.

So I’m not sure I wouldn’t talk to a person who is not curious. I think it would have more to do with what the person happens to be curious about. I don’t pretend to be curious about everything. Nobody ever is. Even Leonardo da Vinci wasn’t curious about literally everything! He was curious about most things, but still not everything.

You chart curiosity’s function both evolutionarily speaking, as a species, and also for us as individual people, developing as children and on into adulthood.

There have now been done quite a few experiments with children, and one of the things they found was that children apparently try to learn as much as they can about their environment in terms of cause and effect. Experiments have shown that children really don’t give up until they understand this, and when they have certain expectations and those expectations are violated by what they see, then they tend to explore more along those lines to try to find out why their expectations were violated and whether they should revise the way they think about that.

In adults, what has been found is that they tend to explore a wide range of options to know what best to do, and also they tend to do things that are not too hard but also not too easy, to improve their competence and to be able to make predictions with fewer errors.

Now you throw into this the evolutionary perspective, where I must say I speculated. And that was to say that I think that curiosity played a very major role in the way the brain of humans, of homo sapiens, evolved. A series of things led to the fact that our brains increased very, very fast, even compared to other primates. We have some advantage as primates already over other species in that we can pack more neurons into our cerebral cortex, but even compared to other primates, our brain evolved and became much larger. I think that in an indirect way there was some feedback there in which curiosity helped.

For example, early humans saw that fire does something. But how did they decide that they could use that fire to cook their meat? That had to be some sort of curiosity, right? I mean, they once put this meat in and tried to eat it, and they saw that it tasted better or they could chew it better. And similarly with other such things, like the preparing of tools and eventually language. It’s very complicated, how that actually came about, but the thought is that it may have been related to some rituals or to some wondering. And those rituals and wonderings, they were all a result of curiosity: people wanted to know, why are things like this, what is it that causes that, and so on. And that led to the early religions or religious thoughts, and eventually to science. So I see curiosity as a necessary ingredient in the stew of things that led to the evolution of the human brain.

You include two images early on in the book. There’s a photograph of scientists, including you, gathered around a computer screen, looking at it with great curiosity—and then the Rembrandt painting “The Anatomy Lesson of Dr. Nicolaes Tulp,” in which those gathered around the anatomy lesson are displaying an almost identical posture. I hadn’t noticed until I looked at those two images back-to-back that when we’re curious, we make this gesture where we shove our heads forward, almost off our bodies! Why do you think we make that gesture when we’re curious?

I think it has to do partly with our perception systems. When we are curious about something, we want to see it better, or we want to hear better what is being said. So I think it is natural for us to lean towards the source of curiosity.

You asked some of your interviewees about their curiosity as children, and whether they are as curious today as they were as children. So I wondered if I could throw that question back at you.

Yes. [laughter] So, as you may have noticed, most of them more or less said that they are as curious or more, and I think that’s the way I feel too. I may not be curious about exactly the same things, but I definitely am as curious as I was.

Most people think children are very curious, and that adults somehow lose their curiosity. But I think that’s not exactly true. What I think we do lose is some of the search for novelty and the ability to be surprised. Children have a lot of questions because they are constantly surprised or, again, want to understand cause and effect. Those are things that adults already know or lose interest in somewhat. They are a little bit more set in their ways, and they are not searching as much for novel, surprising experiences.

But at the same time, epistemic curiosity, namely the love of knowledge and wanting to acquire more knowledge, actually appears to be fairly stable across adulthood. And so while people may not want to go bungee jumping or something, to be curious about what’s going to happen there, they may still be interested in finding out something about the anthropology of the Mayans or the Incans, or… So they are very curious, but they go more towards epistemic and less toward diversive or perceptual curiosity.

That said, one of your ideas for adults wishing to maintain their curiosity is to do something that’s surprising or that seems out of character for them. Do you take that suggestion yourself, and could you give me an example of something you’ve done in adulthood to purposely surprise yourself?

An example for that in my case is that while I always liked music, classical music in particular, I never thought of actually getting involved with that. But in the past few years, I got involved with a composer and together we created this thing which is called “The Hubble Cantata,” which played at the Kennedy Center in D.C. and will play at the L.A. Opera. I didn’t write the music, Paola Prestini did, but I in some sense inspired the piece by explaining to her and to the librettist and to the filmmaker what this science was all about, and why it’s exciting. And I followed the creation of this piece in all its stages. This was something completely new for me.

In a way it seems to me that researching and writing this book was a way of introducing some novelty into your work life, given it’s something that interests you but is not along the lines of the astrophysics that you typically research.

You are absolutely right. In fact, if you look at all my books, with the exception of the first, I tend not to write books that basically amount to taking my day job, which is researching astrophysics, and just putting that in a language that the general public can understand. There is a lot to be said for that, but there is a part of me that still enjoys the research. If all I do is take my personal research and turn that into a simpler language, that doesn’t require too much outside research on my part and I don’t find that particularly attractive. So I always try to pick topics that force me to do a vast amount of research. But you are absolutely right, this book required in that sense the most effort because I went the farthest from my typical research.

As a writer who often talks to other writers and artists, I haven’t had extensive contact with science in my adult life. So I’m hoping I can use this opportunity to ask you some very basic questions, such as: What exactly is astrophysics?

Astrophysics is applying physics to explaining the universe, basically—what stars do, what planets do, what galaxies do and what the universe does as a whole. How do planets and stars and galaxies form? Why is the universe expanding? This is what astrophysics does.

You worked on theHubble Telescope for a long time, up until about two years ago. When I think about a telescope, I think about something on the earth that is looking into space. But the Hubble Telescope was launched into space and is a satellite, if I’m correct. So maybe you could explain what it is and how it works, exactly.

There are many ground-based telescopes of various sizes and various wavelengths of radiation. But we also have a good number of telescopes in space. In the case of Hubble, it is relatively not that high an orbit, it’s something like three hundred miles up from the ground, but yes, it orbits the earth. There are other satellites or observatories that have more peculiar orbits that go much farther from earth. The James Webb Space Telescope, for example, which will be launched next year, will be in an orbit that puts it about a million miles from earth.

So these are telescopes that are in space and because they are in space, they don’t get interference from the earth’s atmosphere. See, the earth’s atmosphere both blocks certain types of radiation and blurs images of various objects because of motions within the atmosphere. So the idea is to put telescopes in orbit above the atmosphere so that you can get a sharper vision, you can see in wavelengths that are blocked by the atmosphere that you cannot see from earth, like ultraviolet light.

This makes so much sense. So if I’m correct, a sliver of the research that you’ve participated in has to do with discovering that the universe is expanding at an ever increasing rate rather than a decreasing rate, is that right?

Right. Correct. Now I should emphasize that I am a theorist. I am not an observer myself. But typically I am the one who tries to explain the observations and do theoretical models, using the laws of physics to explain what we see. But yes: two groups of astronomers working independently discovered in 1998 that the expansion of our universe is accelerating. Before that, we thought that it might be slowing down. And I have been involved in some of the observations that followed up on that and also in some of the theoretical modeling of this phenomenon.

What are the implications?

If the universe continues to accelerate the way it does now, then it will eventually reach a fate of very cold death. Now, we’re talking many trillions of years from now. So it’s not something to worry about immediately, but that’s what will happen.

In fact, even before the cold death, maybe about a trillion or two trillion years from now, if there are still astronomers living here—not necessarily on earth, but maybe in the solar system or some nearby solar system—then they would actually not see any of the galaxies that we see today. They will only see the galaxy that they are in, because everything else will have shifted out of view for them. So a trillion years from now, astronomers will think that there is only their galaxy in the universe. And so we better make good records of everything so they will know that was not the case.

When I think of the universe expanding, I then think about what is it expanding into, and that thought feels exciting but also kind of very terrifying. That brings to mind what you write about toward the end of the book, which is that curiosity is the best remedy for fear. So maybe you can just talk about that a little bit in relationship to how you feel when you think about this crazy thing.

Right, exactly. We tend to fear the unknown. Once we know about something, it just becomes the subject of study, and we’re not afraid of it anymore. So in this particular case, yes, you are thinking in those terms: what is it expanding into? There is some unknown there, and therefore you feel a certain fear from that.

But the best way to describe it is the following. Imagine that the entire universe is the surface of a balloon. If you live in that universe, then you are a painted dot on that surface. There is nothing outside the balloon, there is nothing inside, it doesn’t exist for you. All your universe is on the surface. Now imagine that this balloon is inflating. Now, it is not inflating into anything, because it inflates into a dimension that doesn’t exist in your universe.

Ohhh.

Right? Your universe is just the surface. But what you would still see, as this is inflating, is that every other point painted on the surface of the balloon is moving away from you. So you will see everything expanding and you will discover that your universe is expanding—but it is not expanding into anything that exists for you. Okay? So that’s the situation we’re in.

Oh, that’s really helpful! And yes, much less frightening. So talking about feelings about these very heady concepts, there’s thisepisode of This American Life about Fermi’s Paradox. One of the reporters, David Kestenbaum, used to be a physicist before he became a reporter. Basically, Fermi’s Paradox brings him to tears, it makes him so, so sad to contemplate us being alone in the universe. It just makes him feel very lonely. So I was curious if you also feel that way, or if there are any scientific questions that that evoke not a dispassionate or curious response in you, but a surprisingly emotional response.

I feel somewhat less emotional about the search for life elsewhere because it’s a topic I have been very involved with. The Fermi Paradox basically is: If there are other intelligent civilizations out there, how come we haven’t seen them? And that raises the possibility that maybe there are not other intelligent civilizations, at least in our Milky Way Galaxy, because other galaxies are too far away to think about. But the thing is that we have made very, very serious progress on this in the past few decades and will continue to do so. And the progress we have made is that until the mid-nineties, so we’re talking just about twenty years ago, we did not know of a single planet revolving around another star other than the sun. We only knew the planets in our own solar system.

We now have directly detected thousands of such planets around other stars. And in fact we realized that in our own Milky Way Galaxy, there are billions and billions of earth-sized planets orbiting stars a bit like the sun in that sort of Goldilocks zone, which is neither too cold nor too hot, so that it allows for liquid water on the surface. That we already know. Okay? There are a billion such planets in our Milky Way.

Now, in the next phase, what we will try to do after the James Webb Space Telescope and another telescope named TESS are launched next year, is start to characterize the atmospheres of some of these planets: Can we find water? Can we find oxygen? Things that we call biosignatures, namely, signs that maybe there is some life on those planets. And by life now I mean microbial life, plant life—it doesn’t need to be very sophisticated life or very complex life, okay?

So we are likely to know whether we’ll find such life on extrasolar planets within the next two to three decades, I would say. This already will give part of the answer to whether life itself is very rare or not. With some luck, within three decades, we will either be able to say that we have found some compelling biosignatures, or, if we haven’t found anything, then the probability of having life on such rocky planets around such stars is less than, say, ten percent. At the same time, we are also engaged in more searches for intelligent life. You may have also heard about this billionaire, Yuri Milner, who gave a hundred million dollars for this search called Breakthrough Listen—so we will have the answers to that, too.

So basically, we are for the first time in human history in a state where within a few decades, we may be able to start really addressing Fermi’s Paradox. And to me, that’s the thing: it’s through curiosity that you suddenly don’t fear. You just study.

Do you have a hope that either we do find that there is life elsewhere, or that we don’t—which means it’s so extraordinary that life happened at all?

I would be absolutely amazed if we discover that there is absolutely nothing out there. I would be amazed. Because that would make us way too special. It would also put an enormous burden on our shoulders. Unfortunately, I am relatively old, so I’m not sure I would actually know the answer during my lifetime. I don’t know how old you are, but you are presumably younger, and maybe you will know the answer.

You might not be comfortable speculating on this or not want to delve into politics, but I would be remiss to not bring up the current administration in a discussion of curiosity. So I’m wondering if you have any thoughts about the role curiosity or the lack thereof has played in the current political climate?

I’m not going address any particular administration, but I’m going make a few general comments. You cited me as saying that curiosity is the best remedy for fear. And I strongly believe in that, which means that it is through curiosity and the love of knowledge that you get informed and are able to make informed decisions. Because you always want a population that makes informed decisions, the way is to encourage curiosity and not to suppress it. And so you want high-ranking politicians to have science advisors, for example, that would help them make decisions that are truly informed and based on scientific facts. That’s one clear thing.

The other thing is you want to encourage all of those activities that foster curiosity and increase knowledge. So I’m talking about supporting scientific research, supporting medical research, supporting the arts, supporting open conversations, supporting libraries. So that is my general philosophy. I think that increasing curiosity can only act to the good of society. And I’m talking about this curiosity that’s love of knowledge and so on—I’m not talking about eavesdropping on people’s phones or things like that when not necessary. So yes. Any attempts to suppress curiosity, like we have seen on part of some totalitarian regimes, are all very, very bad signs for a society.

To end on a hopeful note and as an antidote to what you were just speaking about, could you speak about some of the ways to encourage curiosity in children?

One thing is, don’t tell them answers, just ask them questions. And when you ask them the question, don’t give an immediate answer. Suppose they ask you something. You always come back with, “Well, why do you think?” They will probably say something. Find a way for them to actually test whether what they said is correct or not. That is a very good way to have a conversation that encourages both perceptual and epistemic curiosity, both being surprised by something and then trying to gather the knowledge that is required to answer the question.

A second thing that I heard from one of the people I interviewed and I thought was really interesting is the following: Children are often interested in particular topics—dinosaurs, for example, fascinate American children especially. So instead of starting a curriculum, say, with something that you think is interesting, start with something they think is interesting, like dinosaurs. From that, you can eventually lead to other topics that you know you think they should know about and study. But start with the topics that interest them most, rather than from the beginning imposing on them.

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